In a very real sense, automation has "attacked" humanity and declared jurisdiction over properly done jobs that human beings would normally do (such as sorting mail properly). I once knew someone that owned 2 houses 2 miles apart on the same road with the same phone number (they were the only resident) and had to travel back and forth to get all of their mail until they used the NINE digit zip code. The last 2 digits specify (in a large building in a heavily populated city, they specify half the apartments) your house/block/neighborhood. Check at this site (you only need a partial address, not even a zip code)...
After you get the results of the search, click on one of the pdf choices. That will show you the computer bar code for your address (double check the bar code with your post office and send a test letter to yourself WITHOUT the bar code hoping that the last two digits are good enough in your future correspondence).